Low-power, compact, resilient system and method for physiological monitoring

• US 8,849,387 B2
• Filed: 05/30/2013
• Issued: 09/30/2014
• Est. Priority Date: 05/30/2012
• Status: Active Grant

• Current Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Original Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Inventors: Gilbert, Barry, Haider, Clifton, Felton, Christopher, Schwab, Daniel
• Primary Examiner(s): Koharski, Christopher D
• Assistant Examiner(s): CAREY, MICHAEL JAMES
• Application Number:
  US13/906,316
• Publication Number:
  US 20140012143A1
• Time in Patent Office: 488 Days
• Field of Search: 600/509, 600/520, 600/521, 600/523
• US Class Current: 600/520
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/182 Electrical shielding, e.g. using a Faraday cage
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/1101 Detecting tremor
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval

Abstract

A monitor of a physiological parameter of subject under test to which the monitor is attached, in operation. The monitor includes a set of accelerometers operating in different ranges of acceleration and a physiological sensor. The physiological sensor may include an ECG circuit producing an output data characterizing the subject as a function of a degree of motion and/or reorientation of the monitor or an oximeter device. The process of monitoring includes a determination of R-wave of the subject.

Claims

1. An article of manufacture, comprising:

a monitor unit including, on a single integrated board,

motion sensors configured to collect first data, representing orientation and motion of the article, simultaneously in multiple ranges of acceleration, wherein a motion sensor is configured to generate a first output,

a physiological sensor enabled to collect second data representing a physiological parameter and generate a second output,

a data-logging unit including tangible non-transitory storage medium,

a controller in operable communication with said motion sensor and the physiological sensor, the controller configured to receive the first and second outputs and route data associated with at least one of the first and second outputs to said data-logging unit,

a clocking device connected to the controller and configured

(i) to produce a time stamp that is associated with a) said received at least one of the first and second outputs and b) synchronization data, and that is configured as a reference for time-alignment of data received from multiple sensors, and

(ii) to activate said monitor unit without an input from the user;

and

an electrically-conducting lead electrically connected to a port of the monitor unit.

2. An article according to claim 1, wherein the physiological sensor includes an electrocardiographic (ECG) circuit in a two-electrode configuration or a three-electrode configuration, such that said circuit is configured to operate continuously during a two-week period with a nominal current draw of 100 microAmperes and a nominal power consumption of 0.3 mW in said two-electrode configuration or with a nominal current draw of 135 microAmperes and a nominal power of 4 mW in said three-electrode configuration.

3. An article according to claim 1, wherein the motion sensor includes multiple accelerometer units enabling, aggregately and in response to an input applied to the monitor unit, said multiple ranges of acceleration.

4. An article according to claim 1, wherein the motion sensor and the physiological sensor are operable independently from one another, wherein independent operation of the motion sensor and the physiological sensor includes at least one of being powered, having the first and second outputs sampled in frequency, and having the first and second outputs sampled in amplitude.

5. An article according to claim 1, further comprising

a programmable data processor in communication with the data-logging unit,

wherein the physiological sensor includes an electrocardiographic (ECG) circuit, and

wherein said storage medium has computer readable program code disposed therein which causes the programmable data processor

to process raw data acquired from a sensor to form converted data mapped to a range of voltages defined by a predetermined minimum value of voltage and a predetermined maximum value of voltage;

to remove a direct-current voltage baseline from the converted data to form resulting data; and

to calculate a time-derivative of the resulting data to increase sensitivity of detection of an R-wave associated with a subject with the monitor unit that has been juxtaposed to the subject.

6. An article according to claim 5, wherein program code further causes the programmable data processor

to set a threshold and a refractory period, of operation of the monitor unit, that are physiologically relevant to the detection of the R-wave;

to statistically evaluate the likelihood of presence, as represented by the second output, of a useful R-wave as opposed to an artifact; and

to ignore, for the purposes of data processing and based at least in part on extreme amounts of motion at points of predicted artifact, a time-period associated with a measurement and corresponding to a statistically corrupted R-wave.

7. An article according to claim 5, wherein the monitor unit further comprises a transmitter in operable communication with the controller, the transmitter enabled to transmit routing data associated with at least one of the first and second outputs to the programmable data processor.

8. An article according to claim 1, further comprising a display unit in operable communication with the programmable data processor and enabled to form a visually-perceivable representation of a status of at least one of the first and second outputs.

9. An article according to claim 1, further comprising a housing shell defining an inner volume, said housing shell enclosing the monitor unit and dimensioned to allow juxtaposition of the monitor unit with a portion of a body of a wearer of the monitor unit, wherein a motion of arms of the wearer as detected by the motion sensor is minimized, and wherein mechanical interference with clothing of the wearer is minimized.

10. An article according to claim 1, wherein the controller is operably compatible with a multitude of different power battery specifications.

11. An article according to claim 1, wherein the monitor unit further comprises electronic circuitry configured to effectuate at least one of activation and deactivation of the monitor unit in response to a predetermined external event to reduce the amount of at least one of the first and second data.

12. An article according to claim 1, wherein the controller is configured to activate or deactivate the monitor unit only if a switch of the article, once having been physically activated, remains physically activated for a predetermined time interval to generate an indicator of validity of said physical activation of the switch.

13. An article according to claim 1, wherein the physiological sensor includes an oximetry measurement unit configured to effectuate a measurement of one or more of oxygen saturation of a sample tissue, respiration, body temperature, and galvanic skin response.

14. An article according to claim 2, wherein said physiological sensor further comprises a front-end circuit concatenated with said ECG circuit, said front end circuit including

(i) a transceiver and

(ii) a circuit regulator unit configured

to be incorporated into a signal path between said ECG circuit and an antenna of the article when a level of signal received from said ECG circuit by said transceiver falls below a predetermined level, to provide amplification to said signal, and

to be operably by-passed when a level of said signal is above the predetermined level.

15. An article according to claim 1, further comprising a battery to power a component of said article, wherein said port is configured to enable

adjusting of one or more of signal gain and a rate of sampling of the physiological parameter;

downloading of said data received from multiple sensors and said synchronization data;

programming said controller; and

charging said battery.